The present invention is directed to photoresponsive imaging members. More specifically, the present invention is directed to imaging members which contain photoconductive compounds with an azo moiety and a perinone moiety. One embodiment of the present invention is directed to an imaging member which comprises a conductive substrate and a photogenerating layer containing a compound selected from the group consisting of: ##STR2## and mixtures thereof, wherein Cp represents a coupler group.
Photoresponsive imaging members are known, such as those consisting of a homogeneous layer of a single material such as vitreous selenium, or composite layered devices containing a dispersion of a photoconductive composition. An example of a composite xerographic photoconductive member is described in U.S. Pat. No. 3,121,006, which discloses finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. Imaging members prepared according to the teachings of this patent contain a binder layer with particles of zinc oxide uniformly dispersed therein coated on a paper backing. The binders disclosed in this patent include materials such as polycarbonate resins, polyester resins, polyamide resins, and the like, which are incapable of transporting injected charge carriers generated by the photoconductive particles for any significant distance. Accordingly, the photoconductive particles must be in a substantially contiguous particle to particle contact throughout the layer for the purpose of permitting the charge dissipation required for a cyclic operation.
Photoreceptor materials comprising inorganic or organic materials wherein the charge generating and charge transport functions are performed by discrete contiguous layers are also known. Additionally, layered photoreceptor members are disclosed in the prior art, including photoreceptors having an overcoat layer of an electrically insulating polymeric material. Other layered photoresponsive devices have been disclosed, including those comprising separate photogenerating layers and charge transport layers as described in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Photoresponsive materials containing a hole injecting layer overcoated with a hole transport layer, followed by an overcoating of a photogenerating layer, and a top coating of an insulating organic resin, are disclosed in U.S. Pat. No. 4,251,612, the disclosure of which is totally incorporated herein by reference. Examples of photogenerating layers disclosed in these patents include trigonal selenium and phthalocyanines, while examples of transport layers include certain aryl diamines as illustrated therein.
In addition, U.S. Pat. No. 3,041,167 discloses an overcoated imaging member containing a conductive substrate, a photoconductive layer, and an overcoating layer of an electrically insulating polymeric material. This member can be employed in electrophotographic imaging processes by initially charging the member with an electrostatic charge of a first polarity, followed by exposing it to form an electrostatic latent image that can subsequently be developed to form a visible image.
U.S. Pat. No. 3,574,181 discloses disazo compounds useful as coloring agents. Composite electrophotographic photosensitive materials containing various azo compounds are disclosed in U.S. Pat. No. 4,618,672, wherein bisazo compounds particularly suitable for use in the charge generating layer of a layered electrophotographic photoconductor are illustrated. Similarly, an article by M. Hashimoto entitled "Electrophotographic Sensitivity of Fluorenone Bisazo Pigments," Electrophotography, Vol. 25, No. 3 (1986), discloses disazo compounds as charge generating materials in electrophotographic layered photoreceptors. Further, Japanese Patent Kokai No. 54-20736 discloses disazo pigments as constituents in electrophotographic processes. Japanese Patent 58-177955 also discloses many disazo compounds suitable for use in the photosensitive layer of an electrophotographic device.
U.S. Pat. No. 4,713,307, the disclosure of which is hereby totally incorporated by reference, also discloses photoconductive imaging members containing a supporting substrate, certain azo pigments as photogenerating materials, and a hole transport layer that preferably contains an aryl diamine compound dispersed in an inactive resinous binder.
U.S. Pat. No. 4,797,337, the disclosure of which is totally incorporated herein by reference, discloses a photoconductive imaging member comprising a supporting substrate, a hole transport layer, and a photogenerating layer comprising specific disazo compounds.
Additional references illustrating layered organic electrophotographic photoconductor elements with azo, bisazo, and related compounds include U.S. Pat. Nos. 4,390,611, 4,551,404, 4,596,754, Japanese Patent 60-64354, U.S. Pat. Nos. 4,400,455, 4,390,608, 4,327,168, 4,299,896, 4,314,015, 4,486,522, 4,486,519, 4,555,667, 4,440,845, 4,486,800, 4,309,611, 4,418,133, 4,293,628, 4,427,753, 4,495,264, 4,359,513, 3,898,084, and Japanese Patent Publication 60-111247.
U.S. Pat. No. 4,755,443 discloses a photoreceptor for electrophotography which comprises a charge carrier generating material and charge transport material wherein one charge generating material is a metal phthalocyanine or a metal-free phthalocyanine. The layer containing the generator material also contains an organic amine. Other carrier generating substances can be used in combination with the phthalocyanine generator material, including azo pigments, anthraquinone dyes, perylene dyes, polycyclic quinone dyes, and methine stearate pigments.
U.S. Pat. No. 4,424,266 discloses an electrophotographic photosensitive element having a conductive support and a photosensitive layer comprising a carrier generating phase layer containing a carrier generating material selected from the group consisting of perylene dyes, polycyclic quinones, and azo dyes, and a carrier transporting phase layer containing a hydrazone carrier transporting material. The carrier generator materials can be used either singly or in combination.
U.S. Pat. No. 4,882,254, the disclosure of which is totally incorporated herein by reference, discloses a layered photoresponsive imaging member which comprises a supporting substrate, a photogenerator layer comprising a mixture of first and second pigments, and an aryl amine hole transport layer. The mixture of pigments is selected from perylenes and phthalocyanines, polycyclic quinones and phthalocyanines, or perinones and phthalocyanines.
Japanese Patent Publication J01-198-763 discloses an electrophotographic photoreceptor containing a bisazo series compound in a photosensitive layer formed on a conductive support. A charge transport material is used with the bisazo pigment as a charge generation material, such as 2,4,7-trinitrofluorenone, tetracyanoquinodimethane, carbazole, triarylalkane derivatives, phenylenediamine derivatives, hydrazone compounds, or stilbene derivatives.
Photoresponsive imaging members containing perinone and perylene compounds are also known. For example, European Patent Publication 0040402, DE3019326, filed May 21, 1980, discloses the use of N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments as photoconductive substances. Specifically, there is disclosed in this publication evaporated N,N'-bis(3-methoxypropyl)perylene-3,4,9,10-tetracarboxyldiimide dual layered negatively charged photoreceptors with improved spectral response in the wavelength region of 400 to 700 nanometers. A similar disclosure is contained in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). Further, U.S. Pat. No. 3,871,882 discloses photoconductive substances comprising specific perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. According to the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the dyestuff in a vacuum. This patent discloses dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Additionally, U.S. Pat. No. 3,879,200 discloses imaging members with perinones. Furthermore, layered imaging members with imidazole thiazinoperinone photogenerators and related components are illustrated in U.S. Pat. No. 4,517,270 and in Japanese Laid Open Publications 59-58433/84 and 59-59682/84.
U.S. Pat. No. 4,808,506, the disclosure of which is totally incorporated herein by reference, discloses a layered photoresponsive imaging member which comprises a supporting substrate, an imidazole perinone comprising components with a mixture of cis and trans isomers of a specific formula, including trans indanthrene Brilliant Orange, cis indanthrene Bordeauxs Red, bis-(4,5-dimethyl)benzimidazole perinone and bis-2,3-naphthimidazole perinone, and an aryl amine hole transport layer.
U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, discloses a photoresponsive imaging member comprising a supporting substrate, a vacuum evaporated photogenerator layer which comprises a perylene pigment.
Imaging members with phthalocyanine materials are also known, as disclosed in, for example, U.S. Pat. Nos. 3,594,163, 3,657,272, 3,816,118, 3,862,127, 3,903,107, 3,927,026, 3,932,180, 3,932,454, 4,031,109, 4,098,795, and U.S. Pat. No. Re. 27,117, the disclosures of each of which are totally incorporated herein by reference.
Of background interest is U.S. Pat. No. 4,868,079, which discloses an electrophotoconductor comprising a conductive support and a photoconductive layer comprising a resin binder having dispersed therein an anthranthrone compound, a phthalocyanine compound, and an oxadiazole compound.
Although known imaging members are suitable for their intended purposes, a need remains for imaging members containing bichromophoric photoconductive materials. In addition, a need exists for imaging members containing photoconductive materials with improved photoconductivity. Further, there is a need for imaging members containing photoconductive materials having azo moieties wherein the hole transporting and electron transporting mobility of the azo material is enhanced. There is also a need for imaging members containing photoconductive materials having azo moieties and a perinone moiety wherein the material has enhanced dispersability in polymers and solvents. Additionally, a need remains for imaging members containing photoconductive materials wherein the optical absorption of the material is increased. A need also remains for photoconductive materials having increased optical absorption, thereby enabling the use of reduced amounts of photoconductive material in an imaging member charge generating layer and thus improviding electrical and environmental stability of the member. Further, there is a need for photoconductive materials with enhanced dispersability in polymers and solvents that enable low cost coating processes in the manufacture of photoconductive imaging members.